Hot air furnace



Dec. 27, 1932.

G. w. MILLER 1,891,996

HOT AIR FURNACE Filed Nov. 26, 1930 Z ShQetS-Sheet 1 Dec. 27, 1932. w, ILLER 1,891,996

HOT AIR FURNACE Filed Nov. 26, 1930 2 Sheets-Shee 2 CIJ Patented Dec. 27, 1932 PATENT GECE GEORGE W. MILLER, OF AMERY, WISCONSIN HOT AIR FURNACE Application filed November 26, 1930. Serial No. 498,334.

This invention relates to hot air furnaces and more particularly to improvements in the construction and connection of an improved radiator casing associated with the combustion chamber of a furnace. This application is a continuation in part of my application entitled Hot air furnace Serial Number 381,233, filed July 26th, 1929, as to all subject matter common to both applications.

Radiators or heating drums are commonly utilized in hot air furnaces, usually being connected by a central conduit with the rear of the combustion chamber and having as sociated therewith deflectors or bafiles usually disposed in the radiator casing for assisting the distribution of the hot gases therem. The radiation or heating eiiiciency of most conventional radiator casings is relatively low due to the fact that the hot gases are not thoroughly circulated within the radiator, but quickly pass through the same and out the smoke outlet. With most conventional structures utilized objectionable overheating is usually caused about the passage between the combustion chamber and radiator casing due to the fact that all fire and burning gases are concentrated at this point. The result is that warping and burning of the combustion chamber casing and radiator casing occurs frequently.

It is an object of my present invention to provide a hot air furnace construction which will eliminate the objectionable features above referred to, which will simplify the structure and reduce the cost of radiator casings and air heating flues associated with the fire pot and combustion chamber, which will effect and insure a thorough circulation and distribution of the hot and burning gases which enter the radiator casing and which will materially increase the heating efficiency of hot air furnaces.

More specifically it is an object to provide a simple, economical furnace construction which includes a radiator casing disposed at the rear of the furnace casing proper and communicating with the combustion chamber of the furnace through a pair of widely spaced unobstructed passages of considerable cross sectional area disposed preferably above the fire pot and fire brick.

Another object is to provide an improved structure for hot air furnaces'wherein an ef- "cient radiator and an air heating flue are formed by means of a casing, a substantial portion of which may be integrally connected with the casing of the furnace defining the combustion chamber and wherein the smoke outlet is disposed at the lowest point of the radiator thereby increasing the distribution and circulation of the hot gases throughout the radiator casin and facilitating the provision of an efiicient check draft and means whereby the radiator casing may be cleaned.

Still another object is to provide an improved furnace construction of the type described wher in the outlets to the radiator casing are disposed at opposite sides of the combustion chamber, wherein the hottest and burning gases are held in the upper portions of the combustion chamber and radiator during complete combustion and wherein the body or outer casing of the furnace proper and radiator may be constructed as one unit, dispensing with the necessity of joints when the furnace is set up.

These and other objects and advantages of the invention'will be fully set forth in the following description made in connection with the accompanying drawings, in which like reference characters refer to similar parts throughout the several views, and in which Fig. 1 is a vertical section taken centrally through a furnace embodying my invention and Fig. 2 is a cross section taken on the line 22 of Fig. 1.

In the drawings the cylindrical exterior casing of my furnace is indicated by the numeral 3 having a dome 4 at the upper end thereof with which a series of distributing pipes 5 communicate.

The furnace structure proper is mounted Within casing 8 in spaced relation thereto and comprises a fire box 6, as shown, of circular cross section and lined with fire brick 7. A suitable grate 8 is mounted at the bottom of the fire pot and disposed above the ash pit 9. The ash pit has the usual extended doorway 10 provided with an ash door 11 and the charging door closes an extended doorway 13 communicating with the upper portion of the fire pot. The combustion chamber 1a preferably constructed from metal may be a continuation of the metal casing of the furnace proper and as shown has a somewhat domed upper end 14a.

It will, of course, be understood that the cross sectional shape of the fire pot and com bustion chamber as well as the radiator and 3 air heating flue may be varied considerably, all within the scope of my invention.

I provide a radiator casing 15 at the rear of the fire pot and combustion chamber which comprises spaced inner and outer walls-15a and 15?) respectively and which, as illustrated, is of semi-circular cross section, it being attached to and in part formed integrally with the metal casing of the furnace proper. The upper and lower ends. of the semi-cylindrical radiator casing are of course closed and the-lower end is spaced some distance above the base of the furnace whereby an efficient air heating flue is formed between the radiator and the furnace proper.

Radiator casing 15, as clearly shown in Fig. 2, has communication with the combustion chamber and the furnace at opposite sides of said chamber and through passages preferably extending from the upper edge of the fire brick through substantially the fullheight of the combustion chamber. In

the construction of the furnace the exterior wall 15.?) of the radiator and the exteriorwall of the furnace-proper may be constructed i the radiator and the rear portion of the exterior wall of the furnace proper may constitute an integral casingdeflning the air heating flue. A smoke outlet passage 16 communicates with the central portion of the lower end of radiator 15 and is connected through a check draft box 17 with the vertical smoke outlet flue 18. It will be noted that the check draft box 17 is horizontally aligned with the lower end of radiator casing 15 and that a check draft damper or door 19 is provided at the outer end of the box 17 In operation the hot products of combustion and burning gases will enter the upper portion of radiator casing 15 through the two large communicating passages disposed on opposite sides of thecombustion chamber. The hottest portion of the gases and the burning gases, due to the natural tendency of heat to seek a higher level, will remain in the upper portion of the radiator until complete combustion has been effected and will be thoroughly circulated'and distributed within the entire radiator casing due .to the widely spaced substantial passages at opposite sides of the combustion chamber.

The smoke and products of combustion will be discharged through the central discharge passage 16 at the bottom of the radiator, materially assisting in a thorough distribution and circulation of the hot gases. The entire radiation area of casing 15 is thus maintained at a very high temperature with a resultant From the foregoing description it will be seen that I have provided an extremely simple but highly etficient furnace structure capable of being manufactured at low cost, and adapted to be set up without joining the radiator casing with the furnace proper. Standard fire brick may be utilized in my structure and it is not'necessary to specially prepare'the fire brick to form the communicating passages between the combustion chamberv and the radiator.

It will, of'course, be understood thatvarious changes may be made in the form, details, proportions and arrangement of the'parts, without departing from the scope of'my invention, which, generally stated consists in a device capable of carrying out the objects above set forth and in the novel parts and combinations of parts disclosed and defined in the appended claims. a

, What is claimed is 1. In a hot air furnace, an exterior casing of substantially elliptical cross section, an

inner casing of substantially crescentv shape in cross section dividing the interiorofsaid first mentioned casing to form a substantially cylindrical furnace chamber, a radiator chamber of arcuate cross section and an air heating flue between said chambers, a fire pot disposed in the lower portion of said furnace chamber, the portion of said furnace chamber above said fire pot constituting a combustion chamber, said combustion chamber having open communication with said radiator chamher through widely spaced longitudinal passages extending substantially the full height a V of said combustion'chamber.

2. In a hot air furnace, a vertical cylindrical main furnace casing having a fire pot in the lower portion thereof and defining a cylindrical combustion chamber above said fire pot, a radiator casing of substantially arcuate cross section disposed vertically atthe rear of said main casing and cooperating with said main casing to define an upward- -'lyextending air heating flue, said radiator casing having longitudinal ends closed below the upper edge of said fire pot and having unrestricted communication tangentially with said combustion chamber throughout substantially the height of the latter and a smoke outlet passage communicating with the central and lower portion of said radiator casing.

In testimony whereof I afiix my signature.

GEORGE W. MILLER. 

